Swimming pool cleaners using valves of different kinds to substantially intermittently cut off flow through the pool cleaner are now well known and widely used. The cut off or substantial interruption of flow induces forces which cause the pool cleaners to move in stepwise manner across the surface being cleaned. All the flow through the cleaner passes through this cut off valve, an example of which is described in my U.S. Pat. No. 4,769,867 (which patent is incorporated herein in its entirety by this reference).
The interruption of flow can have a deleterious effect on the pump assembly causing the flow through the cleaner and can result in pump starvation.
It has now been found that a fairly constant outlet flow from the pool cleaner to the pump assembly can be maintained while the pool cleaner nevertheless operates satisfactorily to clean submerged surfaces.